<template>
  <div class="app-container">
    <!--查询表单-->
    <el-form :inline="true" class="demo-form-inline">
        <!-- 所属分类：级联下拉列表 -->
        <!-- 一级分类 -->
        <el-form-item label="课程类别">
            <el-select
                    v-model="searchObj.subjectParentId"
                    placeholder="请选择"
                    @change="subjectLevelOneChanged">
                <el-option
                        v-for="subject in subjectList"
                        :key="subject.id"
                        :label="subject.title"
                        :value="subject.id"/>
            </el-select>

            <!-- 二级分类 -->
            <el-select v-model="searchObj.subjectId" placeholder="请选择">
                <el-option
                        v-for="subject in subjectLevelTwoList"
                        :key="subject.id"
                        :label="subject.title"
                        :value="subject.id"/>
            </el-select>
        </el-form-item>

        <!-- 标题 -->
        <el-form-item>
            <el-input v-model="searchObj.title" placeholder="课程标题"/>
        </el-form-item>
        <!-- 讲师 -->
        <el-form-item>
            <el-select
                    v-model="searchObj.teacherId"
                    placeholder="请选择讲师">
                <el-option
                        v-for="teacher in teacherList"
                        :key="teacher.id"
                        :label="teacher.name"
                        :value="teacher.id"/>
            </el-select>
        </el-form-item>

        <el-button type="primary" icon="el-icon-search" @click="fetchData()">查询</el-button>
        <el-button type="default" @click="resetData()">清空</el-button>
    </el-form>
      
      <!-- 表格 -->
    <el-table :data="list" border stripe>

      <el-table-column label="编号" width="50">
        <template slot-scope="scope">
          {{ (page - 1) * limit + scope.$index + 1 }}
        </template>
      </el-table-column>

      <el-table-column label="封面" width="200" align="center">
        <template slot-scope="scope">
          <img :src="scope.row.cover" alt="scope.row.title" width="100%">
        </template>
      </el-table-column>
      <el-table-column label="课程信息">
        <template slot-scope="scope">
          <a href="">{{ scope.row.title }}</a>
          <p>
            分类：{{ scope.row.subjectParentTitle }} > {{ scope.row.subjectTitle }}
          </p>
          <p>
            课时：{{ scope.row.lessonNum }} /
            浏览：{{ scope.row.viewCount }} /
            付费学员：{{ scope.row.buyCount }}
          </p>
        </template>
      </el-table-column>
      <el-table-column label="讲师" width="100" align="center">
        <template slot-scope="scope">
          {{ scope.row.teacherName }}
        </template>
      </el-table-column>
      <el-table-column label="价格(元)" width="100" align="center" >
        <template slot-scope="scope">
          <!-- {{ typeof '0' }}  {{ typeof 0 }} {{ '0' == 0 }} -->
          <!-- {{ typeof scope.row.price }}
          {{ typeof Number(scope.row.price) }}
          {{ typeof Number(scope.row.price).toFixed(2) }} -->

          <el-tag v-if="Number(scope.row.price) === 0" type="success">免费</el-tag>

          <!-- 前端解决保留两位小数的问题 -->
          <!-- <el-tag v-else>{{ Number(scope.row.price).toFixed(2) }}</el-tag> -->

          <!-- 后端解决保留两位小数的问题，前端不用处理 -->
          <el-tag v-else>{{ scope.row.price }}</el-tag>
        </template>
      </el-table-column>
      <el-table-column prop="status" label="课程状态" width="100" align="center" >
        <template slot-scope="scope">
          <el-tag :type="scope.row.status === 'Draft' ? 'warning' : 'success'">{{ scope.row.status === 'Draft' ? '未发布' : '已发布' }}</el-tag>
        </template>
      </el-table-column>
      <el-table-column label="创建时间" width="120" align="center">
        <template slot-scope="scope">
          {{ scope.row.gmtCreate.substr(0, 10) }}
        </template>
      </el-table-column>

      <el-table-column label="操作" width="300" align="center">
        <template slot-scope="scope">
          <router-link :to="'/course/info/'+scope.row.id">
            <el-button type="primary" size="mini" icon="el-icon-edit">修改</el-button>
          </router-link>
          <router-link :to="'/course/chapter/'+scope.row.id">
            <el-button type="primary" size="mini" icon="el-icon-edit">编辑大纲</el-button>
          </router-link>
          <el-button type="danger" size="mini" icon="el-icon-delete" @click="removeById(scope.row.id)">删除</el-button>
        </template>
      </el-table-column>
    </el-table>
    <!-- 分页组件 -->
    <el-pagination
      :current-page="page"
      :total="total"
      :page-size="limit"
      :page-sizes="[5, 10, 20, 30, 40, 50, 100]"
      style="padding: 20px 0; text-align: right;"
      layout="total, sizes, prev, pager, next, jumper"
      @size-change="changePageSize"
      @current-change="changeCurrentPage"
    />
  </div>
</template>     

<script>

import courseApi from '@/api/course'
import teacherApi from '@/api/teacher'
import subjectApi from '@/api/subject'

export default {
    
    data(){
        return {
            list:[], //课程列表
            total:0, //总记录数
            page:1, //页码
            limit:5, //每页记录数
            searchObj:{
                subjectId:'' //解决查询表单无法选中二级类别
            }, //查询条件
            teacherList:[], //讲师列表
            subjectList:[], //一级分类菜单
            subjectLevelTwoList:[] //二级分类菜单
        }
    },
    created(){
        this.fetchData();
        // 初始化分类列表
        this.initSubjectList()
        // 获取讲师列表
        this.initTeacherList()
    },
    methods:{
        fetchData(){
            courseApi.getPageList(this.page,this.limit,this.searchObj).then(res =>{
                this.list = res.data.rows;
                this.total = res.data.total;
            });
        },
        initTeacherList() {
            teacherApi.list().then(response => {
                this.teacherList = response.data.items
            })
        },
        initSubjectList() {
            subjectApi.getNestedTreeList().then(response => {
                this.subjectList = response.data.items
            })
        },
        subjectLevelOneChanged(value) {
            for (let i = 0; i < this.subjectList.length; i++) {
                if (this.subjectList[i].id === value) {
                this.subjectLevelTwoList = this.subjectList[i].children
                this.searchObj.subjectId = ''
                }
            }
        },
        // 重置表单
        resetData() {
          this.searchObj = {}
          this.subjectLevelTwoList = [] // 二级分类列表
          this.fetchData()
        },
        // 每页记录数改变，size：回调参数，表示当前选中的“每页条数”
        changePageSize(size) {
          this.limit = size
          this.fetchData()
        },
        // 改变页码，page：回调参数，表示当前选中的“页码”
        changeCurrentPage(page) {
          this.page = page
          this.fetchData()
        },
        removeById(id){
        //选择是否删除
        this.$confirm('此操作将永久删除该信息, 是否继续?', '提示', {
          confirmButtonText: '确定',
          cancelButtonText: '取消',
          type: 'warning'
        }).then(() => {
          return courseApi.removeById(id);
          }).then(response =>{
              this.fetchData();
              this.$message({
              type: 'success',
              message: response.data.message
          });
        }).catch(response => {
          if(response === 'cancel'){
              this.$message({
              type: 'info',
              message: '已取消删除'
            });
          }          
        });
      },
    }
}
</script>